Here's why:
* Ribosomes are the protein synthesis machinery of the cell. They read the genetic code from messenger RNA (mRNA) and use it to link amino acids together in the correct order, creating polypeptide chains that fold into functional proteins.
* Ribosomes can be found free-floating in the cytoplasm or attached to the endoplasmic reticulum (ER).
* When ribosomes are attached to the ER, they are responsible for synthesizing proteins that will be used in the ER, Golgi apparatus, lysosomes, or secreted outside the cell.
* Proteins synthesized by free ribosomes are typically used within the cytoplasm.
So, while the ribosome is the primary protein assembler, the specific location and destination of the protein are determined by whether the ribosome is free-floating or bound to the ER.
